Sierra is trade mark name registered with Berea Hardwoods, who is supplier to many vendors.
Your statement is correct!
However, the name sierra is also used by at least one Chinese supplier (Rizheng), so the name does not assure you it is a Berea product.
There IS a difference--most notably, the transmissions are not the same size, so clearly it is NOT the same kit.
Berea Sierra pen kits are quite reliable and predictable. Berea does make the WoodCraft Wall Street II, which has identical components. There is some confusion whether the plating for WoodCraft is identical to Berea.
Hope this helps,
Ed